Post on 17-Jun-2018
Configuring Priority Queueing
This module describes the tasks for configuring priority queueing (PQ) on a device.
A priority list contains the definitions for a set of priority queues. The priority list specifies which queue apacket will be placed in and, optionally, the maximum length of the different queues.
In order to perform queueing using a priority list, you must assign the list to an interface. The same prioritylist can be applied to multiple interfaces. Alternatively, you can create many different priority policies toapply to different interfaces.
Assign packets to priority queues based on the following qualities:
• Protocol type
• Interface where the packets enter the device
You can specify multiple assignment rules. The priority-list commands are read in order of appearance untila matching protocol or interface type is found.When amatch is found, the packet is assigned to the appropriatequeue and the search ends. Packets that do not match other assignment rules are assigned to the default queue.
• Finding Feature Information, page 1
• How to Configure Priority Queueing, page 2
• Configuration Examples for Priority Queueing , page 6
• Additional References for Configuring Priority Queueing, page 7
• Feature Information for Configuring Priority Queueing , page 8
Finding Feature InformationYour software release may not support all the features documented in this module. For the latest caveats andfeature information, see Bug Search Tool and the release notes for your platform and software release. Tofind information about the features documented in this module, and to see a list of the releases in which eachfeature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T 1
How to Configure Priority Queueing
Defining the Priority List
Assigning Packets to Priority Queues
SUMMARY STEPS
1. enable2. configure terminal3. priority-list list-number protocol protocol-name {high |medium | normal | low} queue-keyword
keyword-value4. priority-list list-number interface interface-type interface-number {high |medium | normal| low}5. priority-list list-number default {high |medium | normal | low}6. end
DETAILED STEPS
PurposeCommand or Action
Enables privileged EXEC mode.enableStep 1
Example:
Device> enable
• Enter your password if prompted.
Enters global configuration mode.configure terminal
Example:
Device# configure terminal
Step 2
Establishes queueing priorities based on the protocol type.priority-list list-number protocol protocol-name{high |medium | normal | low} queue-keywordkeyword-value
Step 3
All protocols supported by Cisco are allowed. Thequeue-keyword argument provides additional optionsincluding byte count, TCP service and port numberassignments, and AppleTalk, IP, IPX, VINES, or XNSaccess list assignments. Refer to the priority-listprotocol command syntax description in theCisco IOSQuality of Service Solutions Command Reference.
Note
Example:
Device(config)# priority-list 1 protocol iphigh list 10
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T2
Configuring Priority QueueingHow to Configure Priority Queueing
PurposeCommand or Action
Establishes queueing priorities for packets entering from a giveninterface.
priority-list list-number interface interface-typeinterface-number {high |medium | normal| low}
Example:
Device(config)# priority-list 3 interfaceethernet 0 medium
Step 4
Assigns a priority queue for those packets that do not matchany other rule in the priority list.
priority-list list-number default {high |medium |normal | low}
Example:
Device(config)# priority-list 3 default high
Step 5
Exits global configurationmode and returns to privileged EXECmode.
end
Example:
Device(config)# end
Step 6
Specifying the Maximum Size of the Priority Queues
SUMMARY STEPS
1. enable2. configure terminal3. priority-list4. end
DETAILED STEPS
PurposeCommand or Action
Enables privileged EXEC mode.enableStep 1
Example:
Device> enable
• Enter your password if prompted.
Enters global configuration mode.configure terminal
Example:
Device# configure terminal
Step 2
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T 3
Configuring Priority QueueingDefining the Priority List
PurposeCommand or Action
Specifies the maximum number of packets allowed in each ofthe priority queues:
priority-list
Example:
Device(config)# policy-list
Step 3
• high-limit--20
• medium-limit--40
• normal-limit--60
• low-limit--80
(Optional) Exits global configuration mode.end
Example:
Device(config)# end
Step 4
Assigning the Priority List to an Interface
SUMMARY STEPS
1. enable2. configure terminal3. interface interface-type interface-number4. priority-group list-number5. end
DETAILED STEPS
PurposeCommand or Action
Enables privileged EXEC mode.enableStep 1
Example:
Device> enable
• Enter your password if prompted.
Enters global configuration mode.configure terminal
Example:
Device# configure terminal
Step 2
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T4
Configuring Priority QueueingAssigning the Priority List to an Interface
PurposeCommand or Action
Specifies the interface, and then enters interfaceconfiguration mode.
interface interface-type interface-number
Example:
Device(config)# interface ethernet 0
Step 3
Assigns a priority list number to the interface.priority-group list-number
Example:
Device(config-if)# priority-group 3
Step 4
Exits interface configuration mode and returns toprivileged EXEC mode.
end
Example:
Device(config-if)# end
Step 5
Monitoring Priority Queueing Lists
SUMMARY STEPS
1. enable2. show queue interface-type interface-number3. show queueing priority
DETAILED STEPS
PurposeCommand or Action
Enables privileged EXEC mode.enableStep 1
Example:
Device> enable
• Enter your password if prompted.
Displays the contents of packets inside a queue for aparticular interface or VC.
show queue interface-type interface-number
Example:
Device# show queue interface-typeinterface-number
Step 2
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T 5
Configuring Priority QueueingMonitoring Priority Queueing Lists
PurposeCommand or Action
Displays the status of the priority queueing lists.show queueing priority
Example:
Device# show queueing priority
Step 3
Configuration Examples for Priority Queueing
Example: Priority Queueing Based on Protocol TypeThe following example establishes queueing based on protocol type. The example assigns 1 as the arbitrarypriority list number, specifies IP as the protocol type, and assigns a high-priority level to traffic that matchesIP access list 10.
access-list 10 permit 239.1.1.0 0.0.0.255priority-list 1 protocol ip high list 10
Example: Priority Queueing Based on InterfaceThe following example establishes queueing based on interface. The example sets any packet type enteringon Ethernet interface 0 to a medium priority.
priority-list 3 interface ethernet 0 medium
Example: Maximum Specified Size of the Priority QueueThe following example changes the maximum number of packets in the high-priority queue to 10. Themedium-limit, normal, and low-limit queue sizes remain at their default 40-, 60-, and 80-packet limits.
priority-list 4 queue-limit 10 40 60 80
Example: Priority List Assigned to an InterfaceThe following example assigns priority group list 4 to serial interface 0:
interface serial 0priority-group 4
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T6
Configuring Priority QueueingConfiguration Examples for Priority Queueing
The priority-group list-number command is not available on ATM interfaces that do not support fancyqueueing.
Note
Example: Priority Queueing Using Multiple RulesWhen classifying a packet, the system searches the list of rules specified by priority-list commands for amatching protocol type. The following example specifies four rules:
• DECnet packets with a byte count less than 200 are assigned a medium-priority queue level.
• IP packets originating or destined to TCP port 23 are assigned a medium-priority queue level.
• IP packets originating or destined to User Datagram Protocol (UDP) port 53 are assigned amedium-priority queue level.
• All IP packets are assigned a high-priority queue level.
Remember that when using multiple rules for a single protocol, the system reads the priority settings in theorder of appearance.
priority-list 4 protocol decnet medium lt 200priority-list 4 protocol ip medium tcp 23priority-list 4 protocol ip medium udp 53priority-list 4 protocol ip high
Additional References for Configuring Priority QueueingRelated Documents
Document TitleRelated Topic
Cisco IOSMaster Commands List,All Releases
Cisco commands
Cisco IOS Quality of ServiceSolutions Command Reference
QoS commands: complete command syntax, commandmodes, commandhistory, defaults, usage guidelines, and examples
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T 7
Configuring Priority QueueingExample: Priority Queueing Using Multiple Rules
Technical Assistance
LinkDescription
http://www.cisco.com/cisco/web/support/index.htmlThe Cisco Support and Documentation websiteprovides online resources to download documentation,software, and tools. Use these resources to install andconfigure the software and to troubleshoot and resolvetechnical issues with Cisco products and technologies.Access to most tools on the Cisco Support andDocumentation website requires a Cisco.com user IDand password.
Feature Information for Configuring Priority QueueingThe following table provides release information about the feature or features described in this module. Thistable lists only the software release that introduced support for a given feature in a given software releasetrain. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1: Feature Information for Configuring Priority Queueing
Feature InformationReleasesFeature Name
The Priority Queueing (PQ) featureallows you to configure priorityqueueing on a device with the useof priority lists.
The following commands wereintroduced or modified by thisfeature: priority-group, prioritylist default, priority list interface,priority list protocol, priority listqueue-limit, show queue, showqueueing priority.
11.2(1)
12.2(27)SBB
12.2(33)XNA
Cisco IOS XE Release 3.2SE
Priority Queueing (PQ)
QoS: Congestion Management Configuration Guide, Cisco IOS Release 15M&T8
Configuring Priority QueueingFeature Information for Configuring Priority Queueing